Direct observation or viewing by sensors is often used for guidance or control of industrial processes. A significant problem typically encountered in the applications is maintaining clear and uninterrupted transmission through a window or path by which the industrial process is viewed. This problem can be substantial in all environments, however when a sensor is tasked to directly observe a process producing smoke, spatter, powder or other airborne debris, the problems of sensor path and window cleanliness becomes critical. This often results in frequently disrupting the process to clean or change windows, or requires the installation of additional complexities such as window blades, shutters, or other mechanisms. Sensors used for tomography, optical pyrometry, laser absorption spectroscopy, or other remote sensing industrial applications must tolerate the dirty environments associated with dirty, particulate laden environments generated by coal combustion, metal spraying, molten metal atomization, and steel making, among others.
Devices intended to house sensors for use in dirty environments often incorporate an air purge in order to maintain viewing window cleanliness. The air purge acts to maintain a flow across the viewing window in order to mitigate deposition of foreign matter originating with the industrial process. In some cases, higher pressure air may be periodically employed in order to provide a short duration higher energy purge for matter which may gather on or around the viewing window over the course of normal purging. See e.g., U.S. Pat. No. 3,021,385 to Summerhayes Jr., et al.; U.S. Pat. No. 4,981,088 to Burris; U.S. Pat. No. 4,969,035 to Dawson; U.S. Pat. Nos. 5,592,217 and 5,831,668 to Hirvonen et al.; U.S. Pat. No. 6,362,889 to Mustonen; U.S. Pat. No. 6,672,725 to VanOsdol; and U.S. Pat. No. 7,522,834 to Heaven et al., among others. Many of these approaches are additionally intended to maintain a positive pressure flowing from the viewing lens into the vessel conducting the process to be observed. The intent of the positive pressure is to prevent foreign matter from approaching the viewing lens from the vessel environment. Other typical approaches for depositions resistant to normal purge pressures include the use of deslagging blades which are periodically deployed across the viewing lens. See e.g., U.S. Pat. No. 4,759,299 to Kennedy.
Generally speaking, the higher pressure purges are effectuated either through an increase in air supply pressure in order to increase the flow rate through static components, or through the inclusion of additional, dedicated higher pressure pathways. Forcing a higher pressure flow through static components increases parasitic energy requirements, and can increase the necessary bulk of the components in order to withstand repeated exposure to higher design pressures. Similarly, additional, dedicated higher pressure pathways increase the volume footprint of the access probe en toto, in addition to incurring additional probe infrastructure. It would be advantageous to provide an access probe whereby a positive pressure in front of a viewing lens could be increased by utilizing a higher pressure to manipulate the geometric relationship between components, such that a higher pressure pathway could be established without significantly altering the compact nature of the access probe. It would be further advantageous if the probe could act to clear occluding debris from around an access port into the vessel as a result of the component manipulation.
The disclosure relates to an access probe intended to allow access for a measurement medium into a vessel generating particulate laden or hazardous environments, such as a coal fired boiler with slagging walls. The access probe is advantageously utilized for the assistance of passive and active remote sensing of phenomena occurring within the vessel environment utilizing remote sensing instrumentation positioned outside the vessel, via access ports extending through the vessel containment. The measurement medium is typically light and the access is typically provided for the purpose of visual access; however the access probe may be advantageously utilized for the assistance of passive and active remote sensing instrumentation utilizing a variety of measurement mediums such as x-rays, ultrasounds, magnetic resonances, radar, sonar, and the like.
Aspects and advantages of the present disclosure will become better understood with reference to the accompanying description and claims.